This invention relates to an apparatus for inspecting ball grid arrays and, more particularly, to a computer controlled gas pressure-backed, touch sensor array apparatus.
A ball grid array (BGA) is an array of solderable balls placed on a chip carrier. The balls contact a printed circuit board in an array configuration where, after reheat, they connect the chip to the printed circuit board. BGAs are known with 40, 50 and 60 mil. spacings in regular and staggered array patterns.
Electronic components employing BGAs need inspection. The prior art does not provide an automated means for measuring the height of the balls on top of the ball grid array, does not have a means for determining the flatness of the ball grid array, nor does it have a means for determining whether the balls have been properly formed or exist at all in their proper positions.
Some prior art methods of contacting conductors, pins or leads on printed circuit boards or chips have used spring based contact sensors or pogo pins. In many applications, the amount of force applied by springs or pogo pins would be detrimental to the ball grid array components.
Therefore, it is a motivation of the invention to provide a highly efficient, rapid and safe BGA inspection system that can measure BGA characteristics like the position and height of BGA balls and warpage of the BGA carrier among others.